1. Field of the Invention
Apparatuses and a method consistent with the present invention relate to a magnetic tape, a magnetic tape cartridge, a magnetic tape drive, and a method for recording data on a magnetic tape.
2. Description of the Related Art
As the high recording density of magnetic tapes advances, a demand for an accurate tracking technique becomes stronger. To meet this demand, at present, servo-tracking signals (servo signals) are recorded on a magnetic tape beforehand, and data is recorded/reproduced on/from the magnetic tape, while the servo signals are read and the tracking on the tape is then adjusted based on the servo signals read.
However, as the recording density is further increased, the time that is required to pinpoint the location of data from a magnetic tape ends up being longer when the data is searched through the tape or when new data is appended thereon. This lowers the level of operating convenience. To prevent this degradation, information regarding the location of data is encoded into servo signals of a magnetic tape, so that data detection is made faster and more efficient. The above servo signals, however, occupy a large area of a magnetic tape, because servo signals and data are typically positioned on the tape, while being separated from each other. This may inhibit the high recording density, thereby causing a problem.
On the other hand, within the content of the current technique, a width (pitch) of a data track and a location of the track on a magnetic tape depend on a magnetic tape drive, thereby making it difficult to produce different widths and locations on a single magnetic tape. To give an example, if a magnetic tape is recorded by a drive in such a way that the width of the data track is formed to be Tw (μm), then this tape cannot be recorded to form a Tw/2 (μm) width. Similarly, a magnetic tape, on which an old model of a magnetic tape drive has recorded data, may not always be recorded by a current model even if it can be reproduced. In other words, compatibility among models, systems, etc. of drives is lacking, thereby causing an additional problem.
Conventionally, methods for sequentially recording data on a magnetic tape have been applied, because it is difficult to record data at desired locations on the track, that is, randomly record data on the tape. Such a sequential data format seems inefficient in view of data accessibility. As methods for improving data accessibility, servo tracking techniques are disclosed in U.S. Pat. Nos. 6,172,837 and 6,411,460. In these methods, servo bands are formed over a full width of a magnetic tape in advance, and by use of a magnetic tape drive, parts of the servo bands are erased and data is recorded on the erased parts.
However, even with these methods, the structure of the erased servo bands and the data format are still determined by a magnetic tape drive. Once a magnetic tape is recorded by a certain drive model, it may not be recorded by another model. In other words, neither different structures of the servo bands nor different data formats are allowed on a single magnetic tape.